Entrez Gene Summary for GLT6D1The GT6 glycosyltransferases gene family, which includes the ABO blood group (ABO; MIM 110300) and GLT6D1, shows a complex evolution pattern, with multiple events of gain and loss in different mammal species. In humans, the ABO gene is considered the sole functional member, although the O allele is null and is fixed in certain populations (summary by Casals et al. (2009) (PubMed 19218399)).(supplied by OMIM, Jan 2011) [Reference: http://www.genecards.org/cgi-bin/carddisp.pl?gene=GLT6D1 ]